Question: The results of a survey of the 40 families at West ES are shown in the graph. During the survey, each family was asked how many children were in their family. What was the average of the families' responses? Express your answer as a decimal to the nearest tenth. [asy] size(150); defaultpen(linewidth(0.8)); add(scale(2,5)*grid(4,2)); yaxis("{Number of Families}",0,10,Ticks(Step=5)); draw(Label("{Children per Family}",align=4*S),(0,0)--(8,0)); for(int i = 1; i <= 4; ++i){ label((string)i,(2*i,0),S); } void drawBar(real x, real height){ filldraw((2*x-0.5,0)--(2*x-0.5,height)--(2*x+0.5,height)--(2*x+0.5,0)--cycle,gray(0.7)); } drawBar(1,10); drawBar(2,10); drawBar(3,10); drawBar(4,10); [/asy]
Solution: The total number of children is $10\cdot1+10\cdot2+10\cdot3+10\cdot4=100$ children. There are a total of $10+10+10+10=40$ families. So the average children per family is $\dfrac{100}{40}=\boxed{2.5\text{ children}}$.